Electrolysis tank superstructure with intermediate gantry, for the production of aluminium

Abstract

The invention concerns a superstructure for a tank for the production of aluminum using the Hall-Heroult process by the electrolysis of alumina in molten cryolite, the tank being formed by a rigid metal heat-insulated casing of elongate parallelepipedic shape, the two ends of which are referred to as heads, and a superstructure formed by at least one rigid beam disposed along the long length of the casing, supporting in particular the anodic bus and the anodes and resting at its two ends on supports disposed at the two head ends of the tank, said superstructure being characterized in that each rigid beam is supported on at least one intermediate gantry in the central part thereof. The gantry may comprise four legs so as to constitute an inherently stable structure or it may be formed by two half-elements each provided with two legs. Preferably, each rigid beam is divided into two equal portions, the central ends of which are supported on the gantry.

We claim: 
     
       1. In a superstructure for a tank for the production of aluminium using the Hall-Heroult process by the electrolysis of alumina in molten cryolite, the tank being formed by a rigid metal heat-insulated casing of elongate parallelepipedic shape, the two ends of the tank comprising heads, and a superstructure formed by at least one rigid beam disposed along the long length of the casing at least supporting an anodic frame structure and the current input members coming from a preceding tank in a series of tanks and the anodes of the tank, and the beam at least resting at its two ends on supports disposed at the two head ends of the tank, the improvement comprising said superstructure having said at least one rigid beam (11) supported on at least one intermediate gantry provided with a horizontal support surface on which said at least one beam rests, and legs, said horizontal support surface being located entirely below said at least one rigid beam without said at least one intermediate gantry passing through said at least one rigid beam. 
     
     
       2. A tank superstructure according to claim 1 wherein the gantry (17) comprises four legs (18) so as to provide a structure which is stable in itself. 
     
     
       3. A tank superstructure according to claim 1 wherein the gantry (17) is formed by two half-elements (20A, 20B) each provided with two legs as at (23A and 23B). 
     
     
       4. A superstructure according to claim 1 wherein the gantry is formed by a single horizontal support beam (27) which is supported on two legs (28). 
     
     
       5. A superstructure according to claim 1, wherein said at least one gantry additionally comprises elements located laterally of said at least one rigid beam and extending from said support surface in a generally upward direction. 
     
     
       6. A superstructure according to claim 5, wherein said lateral elements are connected by a cross-piece located above said at least one rigid beam. 
     
     
       7. In a superstructure for a tank for the production of aluminium using the Hall-Heroult process by the electrolysis of alumina in molten cryolite, the tank being formed by a rigid metal heat-insulated casing of elongate parallelepipedic shape, the two ends of the tank comprising heads, and a superstructure formed by at least one rigid beam disposed along the long lengths of the casing at least supporting an anodic frame structure and the current input members coming from a preceding tank in a series of tanks and the anodes of the tank, and the beam at least resting at its two ends on supports disposed at the two head ends of the tank, the improvement comprising said superstructure having said at least one rigid beam (11) supported on at least one intermediate gantry provided with legs, said at least one intermediate gantry formed by two half elements (20A, 20B), each provided with two legs. 
     
     
       8. A superstructure according to claim 1 or 7 wherein said at least one rigid beam (11) is divided into at least two portions (11A, 11B), the central ends (24A, 24B) of which are supported on the gantry. 
     
     
       9. A superstructure in which according to claim 8 in which the legs (18) or (23A, 23B) or (28) which support the outer ends of the rigid beams (11A, 11B) are supported on the rims (15) of the casing. 
     
     
       10. A superstructure according to claim 5 in which the legs (18) or (23A, 23B) or (28) which support the ends of the rigid beams (11A, 11B) are supported at the outside of the rims (15) of the casing. 
     
     
       11. A superstructure according to claim 7, wherein one said current input member passes between said two half elements. 
     
     
       12. A superstructure according to claim 11, wherein said two half elements each comprises a horizontal support surface, a pair of elements lateral to said at least one rigid beam and extending from said horizontal support surface generally upward, and a cross-piece located above said at least one rigid beam which connects said lateral elements. 
     
     
       13. A superstructure according to claim 7 or 3, wherein said at least one rigid beam is fixed to the gantry element on which it is supported. 
     
     
       14. In a superstructure for a tank for the production of aluminium using the Hall-Heroult process by the electrolysis of alumina in molten cryolite, the tank being formed by a rigid metal heat-insulated casing or elongate parallelepipedic shape, the two ends of the tank comprising heads, and a superstructure formed by at least one rigid beam disposed along the long length of the casing at least supporting an anodic frame structure and the current input members coming from a preceding tank in a series of tanks and the anodes of the tank, and the beam at least resting at its two ends on supports disposed at the two head ends of the tank, the improvement comprising said superstructure having said at least one rigid beam (11) supported on at least one intermediate gantry provided with legs, said at least one rigid beam (11) being divided into at least two portions (11A, 11B), the central ends of which are supported on the gantry. 
     
     
       15. A superstructure according to claim 1, 7 or 14 in which the legs (18) or (23A, 23B) of the gantry (17) are supported freely on the rim (15) of the casing. 
     
     
       16. A superstructure according to claim 1, 7 or 14 in which the legs (18) or (23A, 23B) or (28) of the gantry (17) are supported on the rim (15) of the casing by a means permitting relative displacement. 
     
     
       17. A superstructure according to claim 1, 7 or 14 in which the legs (18) or (23A, 23B) or (28) of the gantry (17) are supported on the rim (15) of the casing by a means permitting relative displacement, the legs at the upstream or downstream side being pivotally mounted on the casing edge by means of an axis which is parallel to the major axis of the tank and the opposite legs on the downstream or upstream side being supported on the casing. 
     
     
       18. A superstructure according to claim 1, 7 or 14 which further includes the gantry being provided with a horizontal support beam (26) or (27) including means for affording protection from thermal radiation from the electrolysis bath. 
     
     
       19. A superstructure according to claim 18 wherein the means for affording protection from radiation from the bath is formed by a thermal screen disposed beneath the horizontal support beam. 
     
     
       20. A superstructure according to claim 18 wherein the means for affording protection from radiation from the bath is formed by a means for rapid removal of the heat absorbed by the horizontal support beam. 
     
     
       21. A superstructure according to claim 20 wherein the means for rapid removal of heat comprises circulation of a heat exchange fluid in heat exchange relationship with the horizontal support beam. 
     
     
       22. A superstructure according to claim 20 wherein the means for rapid removal of heat comprises thermal bridges of good thermal conductivity. 
     
     
       23. A superstructure according to claim 20 wherein the means for rapid removal of heat comprises closed tubes containing an evaporative cooling medium. 
     
     
       24. A superstructure according to claim 1, 7 or 14, wherein the location of one said current input member is defined by a transverse axis X, and the location of said at least one intermediate gantry is defined by a transverse axis Y, and wherein a vertical transverse plane P which passes through said axis X is substantially coincident with a vertical transverse plane P' which passes through said axis Y. 
     
     
       25. In a superstructure for a tank for the production of aluminium using the Hall-Heroult process by the electrolysis of alumina in molten cryolite, the tank being formed by a rigid metal heat-insulated casing of elongate parallelepipedic shape, the two ends of the tank comprising heads, and a superstructure formed by at least one rigid beam disposed along the long length of the casing at least supporting an anodic frame structure and the current input members coming from a preceding tank in a series of tanks and the anodes of the tank, and the beam at least resting at its two ends on supports disposed at the two head ends of the tank, the improvement comprising said superstructure having said at least one rigid beam (11) supported on at least one intermediate gantry provided with legs, wherein the location of one said current input member is defined by a transverse axis X, and the location of said at least one intermediate gantry is defined by a transverse axis Y and wherein a vertical transverse plane P which passes through said axis X is substantially coincident with a vertical transverse plane P' which passes through said axis Y.